JPH02128906A - Motorcycle tire - Google Patents

Abstract

PURPOSE:To improve the grip performance of a tire in its wet and dry states by specifying the length of an inside edge in a sub-groove facing a main groove and distance between the main groove and the sub-groove respectively, and providing a rising part rising from the groove bottom of the sub-groove toward its inside edge. CONSTITUTION:A tire tread is provided with a main groove 10 extending through a tire equator in a circumferential direction of the tire. Both sides of the main groove 10 are provided with sub-grooves 11 which extend in a direction intersecting the main groove 10 and have an inside end 11A breaking off outside the main groove 10 respectively. In his case, a length B of a inside edge 11A1 where the inside end 11A of the sub-groove 11 ends is determined longer than 5mm, and distance A between the inside edge 11A1 and the upper edge 10A1 of the main groove 10 storter than 3mm. In addition to that, a rising part 13 is formed from a groove bottom 11B toward the inside edge 11A1 near the inside end 11A of the sub-groove 11, and the inclination theta of the rising part 13 is determined within an angular range from 40 deg. to 80 deg. in a direction of the sub-groove 11 connecting between a start point R1 an an end point R2 of the rising part 13.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a motorcycle tire that can improve grip performance on both wet and dry road surfaces.

[Conventional technology]

In recent years, with the increase in output and performance of vehicles, high-speed sports driving such as racing on motorcycles has become popular.

On the other hand, for tires used for such sports driving, it is necessary to improve straight-line running stability and drainage performance on wet roads (the main groove passing through the center of the tread has a main groove on both sides that slopes outward toward the direction in which the tire is launched). In many cases, a so-called figure-7 tread pattern with extending wing-shaped minor grooves is adopted.

[Problem to be solved by the invention]

However, this type of tread pattern is usually
), since the inner end al of the sub-groove a is communicated with the main groove, it has excellent drainage performance and improves wet grip performance, but on the other hand, the rigidity decreases at the communicating part C on both sides of the main groove. There is a problem in that the dry grip properties are impaired.

Therefore, it is necessary to prevent this decrease in rigidity in recent years (Fig. 8 (b)).
It has been proposed that the inner end a1 of the sub-groove is the main groove and terminates with a gap d in between, as shown in FIG.

However, in order to sufficiently prevent this decrease in rigidity, the gap d must be set to 61111 or more, preferably 10 amu or more, and as a result, the formation of the gap d actually impairs wet grip performance.

As described above, there is an antinomic relationship between wet grip properties and dry grip properties, and there has been a strong desire to develop something that satisfies both.

The present invention is based on the provision of a raised portion near the inner end of the sub-groove, which allows the gap to be reduced without impairing the rigidity of the gap, thereby improving both wet grip and dry grip, which are contradictory. The company aims to provide tires for motorcycles with the following characteristics.

[Means to solve the problem]

To achieve the above object, the motorcycle tire of the present invention has a tire tread having a main groove continuous in the circumferential direction of the tire, and an inner end extending in a direction intersecting the main groove and facing the main groove. A sub-groove extending along the groove and terminating at an inner edge separated by a distance A from the main groove is provided, and the length B of the inner edge is 5au or more and the path MA is 3 or less. The sub-groove is provided with a raised portion protruding from the groove bottom of the sub-groove toward the inner end edge near the inner end;
The slope θ in the direction of the minor groove connecting the starting point and ending point of the raised portion is 40
The temperature should be above 80 degrees and below 80 degrees.

[Effect]

In this way, the inner edge of the sub-groove having a length of 5 m or more is arranged parallel to the main groove and separated from the main groove by a distance of 311IIIl or less to reduce the gap between the sub-groove and the main groove. At the same time, by increasing the opening width of the sub-groove facing the gap, drainage performance can be improved and wet grip performance can be improved. In addition, by providing a raised portion that rises from the bottom of the sub-groove toward the inner edge and has an inclination θ of 40 degrees to 80 degrees connecting the start and end points of the rise, the rigidity of the gap portion can be effectively increased. This can improve dry grip properties, abrasion resistance, etc.

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

FIG. 1 is a sectional view showing an embodiment of a motorcycle tire (hereinafter referred to as tire) of the present invention, and FIG. 2 is a plan view thereof.

In the figure, a tire 1 includes a tread 2 and sidewalls 3 extending inward in the tire radial direction from both ends of the tread 2.
and a bead 4 located at the inner end of the sidewall 3 in the tire radial direction, and a toroidal carcass 6 is stretched between the bead cores 5 and 5 provided in the bead 4, and its radius A belt layer 7 is arranged on the outside in the direction.

The tread 2 extends outward from the center of the crown approximately parallel to the contour of the crown of the carcass 6, and has a cross-sectional shape in which the tread width TW, which is in a straight line, exceeds the maximum width of the sidewall 3, thereby reducing camber during cornering. −
Thrust is maintained.

In this example, the carcass 6 is composed of two braais whose cords are inclined at an angle of about 70 to 90 degrees with respect to the tire equator, and both ends folded around the bead core 5 from the inside to the outside are connected to the side It terminates at wall 3. Here, the folded end 6a of the carcass 6 located on the outside of the bead 4 extends to a higher position than the folded end 6b of the carcass 6 on the inside of the bead 4, and completely covers the inner folded end 6b. Alleviates stress concentration in the area.

In this example, in order to reinforce the tire lateral rigidity which decreases due to the radial structure, the inner and outer folded edges 6b are
, 6a from the bead bottom are set in the range of 15 to 30% and 20 to 40% of the tire cross-sectional height H,
In addition, a bead apex 9 made of hard rubber extending from the bead core 5 with a gradually decreasing thickness in the direction of the sidewall is arranged in a portion surrounded by the main body of the carcass 6 and its folded ends 6a and 6b, and the sidewall 3 itself is also compared. It is made of hard rubber. In addition, the initial tensile modulus of the braai cord of carcass 6 is 850 kg/gas.
``The following organic fiber cords are used, such as rayon, polyester, nylon, etc.

Further, in this example, the belt layer 7 is a two-layer belt provided with a cord inclined at an angle of about 30 degrees or less with respect to the tire equator, and arranged to have a width covering substantially the entire width of the tread 2. By constructing the britain cord with a high modulus fiber cord having an initial tensile modulus of about 2500 kg/tn'' or more, such as aromatic polyamide fiber, steel fiber, glass fiber, carbon fiber, etc. , the high-speed running performance is improved.The number of plies and the material of the ply cord of the scraps 6 and the belt layer 7 can be changed as appropriate depending on the usage conditions.

Further, as shown in FIGS. 2 and 3, the tire 1 of the present invention has a main groove 10 in the tread 2 that passes over the tire equator Co and extends continuously in the tire circumferential direction, and is linear in this example. At the same time, on both sides of the main groove 10, there are sub-grooves 11 extending in a direction intersecting the main groove 10 and having an inner end 11A cut off outside the main groove 10, which are symmetrical about the tire equator CO. positions and circumferentially spaced apart.

The minor groove 11 has the inner end 11A extending in parallel along the upper edge 10AI of the side wall 10A sandwiching the main groove 10 and terminating at an inner end edge 11A1 separated by a distance A from the upper edge 10A1. Also, the length B of the inner edge 1IAl is 5 seconds or more and the distance A is 31111! It is set below l.

In this way, the inner end edge 11A is parallel to the upper edge 10AI of the main groove, and the distance i1A, that is, the upper surface width of the gap portion 12 between the inner end 11A of the sub-groove 11 and the side wall 10A of the main groove 10 is made small to 3ff11 or less. At the same time, by making the length B, that is, the opening width of the sub-groove 11 extending into the upper surface, larger than 5 mm, it is possible to improve the drainage performance of the water film interposed between the upper surface and the road surface when driving on a wet road surface. This can improve wet grip performance.

Further, the sub-groove 11 has a groove bottom 1 near its inner end 11A.
A protruding portion 13 is provided that protrudes from 1B toward the inner edge 11AI, thereby reinforcing the gap portion 12 and increasing its rigidity, thereby improving dry grip performance and wear resistance. Here, as shown in FIG. 4, the raised portion 13 has an inclination θ of 40 degrees in the direction of the sub-groove connecting a starting point R1 of the sub-groove 11 protruding from the groove bottom 11B and an end point R2 of the protrusion reaching the inner edge 11AI. It is necessary that the angle is greater than or equal to 80 degrees, and thereby the rigidity of the gap portion 12 can be effectively increased without impairing the drainage performance.

Note that if the distance A exceeds 3[ll11] or if the length B is less than 5 am, drainage performance is poor. Also, the slope θ is 4
When the inclination θ is less than 0 degrees, the rigidity of the gap portion 12 cannot be sufficiently reinforced and dry grip properties are reduced, and when the inclination θ exceeds 80 degrees, drainage performance is inhibited.

In this example, the sub-groove 11 is defined in the range from the tire equator co to a position P1 that is spaced outward in the tire width direction by a distance L1 of 0.15 times or more and 0.3 times or less of the tread width TW. A central groove portion 19 passing through the straight ground contact area 15 and a 0.0 mm tread width TW are formed inwardly from the tread shoulder edge 17.
It includes a side groove part 2o passing through the bang grounding area 16 defined in a range up to a position P2 separated by a distance 11iIL3 of 15 times, and a joint groove part 21 connecting between the central groove part 19 and the side groove part 20.

In this example, the central groove part 19 extends in a straight line in which the inclination angle α of the groove center line 21 is in an angle range of 15 degrees or more and 35 degrees or less with respect to the tire equator CO. It maintains the tread rigidity in the circumferential direction at 15, increases the ability to bear stress associated with acceleration and braking during straight running, and improves straight running safety and wear resistance.

Further, the central groove portion 19 may be formed in an arc shape, and in such a case, the inclination angle of the tangent to the groove center line 11 is 15 degrees or more and 35 degrees or less with respect to the tire equator CO.

The side gutter 20 is a side portion in the vang grounding area 16 between the position P2 and a position P3 outward from the position IP2 by a distance #L4 that is 0.7 times or more and 1 times or less the distance L3. By making the slope β of the straight line 12 connecting the groove center point at the position P2 and the groove center point at the position P3 at 50 degrees or more and 90 degrees or less with respect to the tire equator CO, the bank contact area 16 is This maintains the tread rigidity in the width direction, increases the ability to bear lateral stress due to centrifugal force during cornering, improves cornering stability, and suppresses uneven wear near the side grooves 20.

Note that the groove center line of the side gutter 20 is 0.7 of the distance L3.
It is preferable to form an arc having a radius of at least twice the length and no more than 1.8 times the length, whereby the carrying capacity can be gradually increased in response to the lateral stress that increases as the repunk angle increases. .

As shown in FIG. 5, the slope 7a of the groove wall 11a facing the stepping side of the sub-groove 11 is set to 3 to 10 degrees to prevent the groove wall 11a from falling into the groove and prevent uneven wear. , the slope Tb of the groove wall 11b facing the kicking side is 1
By setting the angle to 0 to 20 degrees, it is easy to release water in the groove as the tire rotates.

In addition, FIG. 6 shows another embodiment of the present invention.

In the figure, the main groove 10 has a wavy shape, and the sub-grooves 11 have their inner edges 11AI curved along the main groove IO, and are alternately formed in a staggered manner on both sides of the main groove 10.

Further, other embodiments of the raised portion 13 are shown in FIGS. 7(a) and 7(b).

In FIG. 7(a), the raised portion 13 is raised from a starting point R1 on the groove bottom to an ending point R2 on the upper edge 11A1 via a step 25.

In addition, in FIG. 7(b), the raised portion 13 is located at the starting point R on the groove bottom.
1 to the terminal point R2 below the upper edge 11A1, and in this case, the height hl of the terminal point R2 is equal to the sub-groove depth h.
It is desirable to set it to one-half or more, preferably two-thirds or more.

〔Concrete example〕

A prototype tire with the structure shown in Figures 1 and 2 and based on the specifications in Table 1 was manufactured, and dry grip, wet grip, abrasion resistance, shimmy, and high-speed stability were evaluated through actual vehicle tests. The feeling was evaluated and the results are shown in Table 1 as an index. The above index is shown in Figure 8 (a
) to (b), the feeling evaluation value of the conventional product 1.2 is set as 100, and the larger the value, the better.

〔Effect of the invention〕

Like a ridge, the motorcycle tire of the present invention has an inner edge of the inner end of the sub-groove facing the main groove, which has a length of 5 mm or more, is parallel to the main groove, and has three grooves between it and the main groove. Since they are arranged at the following distances, drainage performance can be improved and wet grip performance can be improved. Further, since the sub-groove has a raised portion at its inner end, the rigidity of the gap between the sub-groove and the first main groove can be increased, and dry grip properties are improved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention, FIG. 2 is a plan view thereof, FIG. 3 is a plan view showing an enlarged inner end of the sub-groove, and FIG.
The figures are a sectional view taken along the line 1-1 in FIG. 3 showing the raised portion, FIG. 5 is a sectional view showing the minor groove, FIG. 6 is a plan view showing another embodiment of the present invention, and FIG. 7(a) - (b) are sectional views showing other embodiments of the raised portion, and Figs. 8 (a) - (b) are route diagrams showing the prior art. 2...Tread, 11A...Inner end, 11B...Groove bottom, R2...End point.

Claims (1)

[Claims] 1 The tire tread has a main groove that continues in the circumferential direction of the tire, and an inner end that extends in a direction intersecting the main groove and faces the main groove, and that extends along the main groove and has a distance A between the main groove and the main groove. A sub-groove is provided that terminates at the inner end edge separating the sub-groove, and the length B of the inner end edge is 5 mm or more and the distance A is 3 mm or less, and the sub-groove is provided with a groove of the sub-groove near the inner end. Providing a protuberance that protrudes from the bottom toward the inner edge,
The slope θ in the direction of the minor groove connecting the starting point and ending point of the raised portion is 40
Motorcycle tires with a temperature of more than 80 degrees and less than 80 degrees.